* {
    margin: 0;
}

.wrapper {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    width: 100%;
}

.wrapper a {
    width: calc(100% / 4);
    max-width: 700px;
    height: auto;
    padding: 2px;
    box-sizing: border-box;
}
.wrapper a img {
    display: block;
    width: 100%;
}
.wrapper a img:hover {
    opacity: 0.7;
}

@media screen and (max-width: 600px) {
.wrapper a {
    width: calc(100% / 2.1);
    margin: 3px;
}
.sp {
  display: none;
}
}